
/*---------------------------------------------------------------------------
 * Copyright (C) 1999,2000 Dallas Semiconductor Corporation, All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY,  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL DALLAS SEMICONDUCTOR BE LIABLE FOR ANY CLAIM, DAMAGES
 * OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * Except as contained in this notice, the name of Dallas Semiconductor
 * shall not be used except as stated in the Dallas Semiconductor
 * Branding Policy.
 *---------------------------------------------------------------------------
 */

package com.dalsemi.onewire.container;

// imports
import com.dalsemi.onewire.OneWireException;
import com.dalsemi.onewire.adapter.OneWireIOException;
import com.dalsemi.onewire.utils.*;
import com.dalsemi.onewire.container.OneWireContainer;


/**
 * Memory bank class for the Scratchpad section of NVRAM iButtons and
 * 1-Wire devices.
 *
 *  @version    0.00, 28 Aug 2000
 *  @author     DS
 */
class MemoryBankScratch
   implements PagedMemoryBank, ScratchPad
{

   //--------
   //--------Static Final Variables
   //--------

   /**
     * Write Scratchpad Command
     */
   public static final byte WRITE_SCRATCHPAD_COMMAND = ( byte ) 0x0F;

   /**
     * Read Scratchpad Command
     */
   public static final byte READ_SCRATCHPAD_COMMAND = ( byte ) 0xAA;

   //--------
   //-------- Variables
   //--------

   /**
    * Reference to the OneWireContainer this bank resides on.
    */
   protected OneWireContainer ib;

   /**
    * block of 0xFF's used for faster read pre-fill of 1-Wire blocks
    */
   protected byte[] ffBlock;

   /**
    * Copy Scratchpad Command
    */
   protected byte COPY_SCRATCHPAD_COMMAND;

   /**
    * Flag to indicate that speed needs to be set
    */
   protected boolean doSetSpeed;

   //--------
   //-------- Protected Variables for MemoryBank implementation
   //--------

   /**
    * Size of memory bank in bytes
    */
   protected int size;

   /**
    * Memory bank descriptions
    */
   protected String bankDescription;

   /**
    * Memory bank usage flags
    */
   protected boolean generalPurposeMemory;

   /**
    * Flag if memory bank is read/write
    */
   protected boolean readWrite;

   /**
    * Flag if memory bank is write once (EPROM)
    */
   protected boolean writeOnce;

   /**
    * Flag if memory bank is read only
    */
   protected boolean readOnly;

   /**
    * Flag if memory bank is non volatile
    * (will not erase when power removed)
    */
   protected boolean nonVolatile;

   /**
    * Flag if memory bank needs program Pulse to write
    */
   protected boolean programPulse;

   /**
    * Flag if memory bank needs power delivery to write
    */
   protected boolean powerDelivery;

   /**
    * Starting physical address in memory bank.  Needed for different
    * types of memory in the same logical memory bank.  This can be
    * used to seperate them into two virtual memory banks.  Example:
    * DS2406 status page has mixed EPROM and Volatile RAM.
    */
   protected int startPhysicalAddress;

   /**
    * Flag if read back verification is enabled in 'write()'.
    */
   protected boolean writeVerification;

   //--------
   //-------- Protected Variables for PagedMemoryBank implementation
   //--------

   /**
    * Number of pages in memory bank
    */
   protected int numberPages;

   /**
    *  page length in memory bank
    */
   protected int pageLength;

   /**
    * Max data length in page packet in memory bank
    */
   protected int maxPacketDataLength;

   /**
    * Flag if memory bank has page auto-CRC generation
    */
   protected boolean pageAutoCRC;

   /**
    * Flag if reading a page in memory bank provides optional
    * extra information (counter, tamper protection, SHA-1...)
    */
   protected boolean extraInfo;

   /**
    * Length of extra information when reading a page in memory bank
    */
   protected int extraInfoLength;

   /**
    * Extra information descriptoin when reading page in memory bank
    */
   protected String extraInfoDescription;

   //--------
   //-------- Constructor
   //--------

   /**
    * Memory bank contstuctor.  Requires reference to the OneWireContainer
    * this memory bank resides on.
    */
   public MemoryBankScratch (OneWireContainer ibutton)
   {

      // keep reference to ibutton where memory bank is
      ib = ibutton;

      // initialize attributes of this memory bank - DEFAULT: DS199X scratchapd
      bankDescription      = "Scratchpad";
      generalPurposeMemory = false;
      startPhysicalAddress = 0;
      size                 = 32;
      readWrite            = true;
      writeOnce            = false;
      readOnly             = false;
      nonVolatile          = false;
      programPulse         = false;
      powerDelivery        = false;
      writeVerification    = true;
      numberPages          = 1;
      pageLength           = 32;
      maxPacketDataLength  = 29;
      pageAutoCRC          = false;
      extraInfo            = true;
      extraInfoLength      = 3;
      extraInfoDescription = "Target address, offset";

      // create the ffblock (used for faster 0xFF fills)
      ffBlock = new byte [96];

      for (int i = 0; i < 96; i++)
         ffBlock [i] = ( byte ) 0xFF;

      // default copy scratchpad command
      COPY_SCRATCHPAD_COMMAND = ( byte ) 0x55;

      // indicate speed has not been set
      doSetSpeed = true;
   }

   //--------
   //-------- Memory Bank methods
   //--------

   /**
    * Query to see get a string description of the current memory bank.
    *
    * @return  String containing the memory bank description
    */
   public String getBankDescription ()
   {
      return bankDescription;
   }

   /**
    * Query to see if the current memory bank is general purpose
    * user memory.  If it is NOT then it is Memory-Mapped and writing
    * values to this memory will affect the behavior of the 1-Wire
    * device.
    *
    * @return  'true' if current memory bank is general purpose
    */
   public boolean isGeneralPurposeMemory ()
   {
      return generalPurposeMemory;
   }

   /**
    * Query to see if current memory bank is read/write.
    *
    * @return  'true' if current memory bank is read/write
    */
   public boolean isReadWrite ()
   {
      return readWrite;
   }

   /**
    * Query to see if current memory bank is write write once such
    * as with EPROM technology.
    *
    * @return  'true' if current memory bank can only be written once
    */
   public boolean isWriteOnce ()
   {
      return writeOnce;
   }

   /**
    * Query to see if current memory bank is read only.
    *
    * @return  'true' if current memory bank can only be read
    */
   public boolean isReadOnly ()
   {
      return readOnly;
   }

   /**
    * Query to see if current memory bank non-volatile.  Memory is
    * non-volatile if it retains its contents even when removed from
    * the 1-Wire network.
    *
    * @return  'true' if current memory bank non volatile.
    */
   public boolean isNonVolatile ()
   {
      return nonVolatile;
   }

   /**
    * Query to see if current memory bank pages need the adapter to
    * have a 'ProgramPulse' in order to write to the memory.
    *
    * @return  'true' if writing to the current memory bank pages
    *                 requires a 'ProgramPulse'.
    */
   public boolean needsProgramPulse ()
   {
      return programPulse;
   }

   /**
    * Query to see if current memory bank pages need the adapter to
    * have a 'PowerDelivery' feature in order to write to the memory.
    *
    * @return  'true' if writing to the current memory bank pages
    *                 requires 'PowerDelivery'.
    */
   public boolean needsPowerDelivery ()
   {
      return powerDelivery;
   }

   /**
    * Query to get the starting physical address of this bank.  Physical
    * banks are sometimes sub-divided into logical banks due to changes
    * in attributes.
    *
    * @return  physical starting address of this logical bank.
    */
   public int getStartPhysicalAddress ()
   {
      return startPhysicalAddress;
   }

   /**
    * Query to get the memory bank size in bytes.
    *
    * @return  memory bank size in bytes.
    */
   public int getSize ()
   {
      return size;
   }

   /**
    * Query to get the number of pages in current memory bank.
    *
    * @return  number of pages in current memory bank
    */
   public int getNumberPages ()
   {
      return numberPages;
   }

   /**
    * Query to get  page length in bytes in current memory bank.
    *
    * @return   page length in bytes in current memory bank
    */
   public int getPageLength ()
   {
      return pageLength;
   }

   /**
    * Query to get Maximum data page length in bytes for a packet
    * read or written in the current memory bank.  See the 'ReadPagePacket()'
    * and 'WritePagePacket()' methods.  This method is only usefull
    * if the current memory bank is general purpose memory.
    *
    * @return  max packet page length in bytes in current memory bank
    */
   public int getMaxPacketDataLength ()
   {
      return maxPacketDataLength;
   }

   /**
    * Query to see if current memory bank pages can be read with
    * the contents being verified by a device generated CRC.
    * This is used to see if the 'ReadPageCRC()' can be used.
    *
    * @return  'true' if current memory bank can be read with self
    *          generated CRC.
    */
   public boolean hasPageAutoCRC ()
   {
      return pageAutoCRC;
   }

   /**
    * Query to see if current memory bank pages when read deliver
    * extra information outside of the normal data space.  Examples
    * of this may be a redirection byte, counter, tamper protection
    * bytes, or SHA-1 result.  If this method returns true then the
    * methods 'ReadPagePacket()' and 'readPageCRC()' with 'extraInfo'
    * parameter can be used.
    *
    * @return  'true' if reading the current memory bank pages
    *                 provides extra information.
    *
    * @deprecated  As of 1-Wire API 0.01, replaced by {@link #hasExtraInfo()}
    */
   public boolean haveExtraInfo ()
   {
      return extraInfo;
   }

   /**
    * Checks to see if this memory bank's pages deliver extra
    * information outside of the normal data space,  when read.  Examples
    * of this may be a redirection byte, counter, tamper protection
    * bytes, or SHA-1 result.  If this method returns true then the
    * methods with an 'extraInfo' parameter can be used:
    * {@link #readPage(int,boolean,byte[],int,byte[]) readPage},
    * {@link #readPageCRC(int,boolean,byte[],int,byte[]) readPageCRC}, and
    * {@link #readPagePacket(int,boolean,byte[],int,byte[]) readPagePacket}.
    *
    * @return  <CODE> true </CODE> if reading the this memory bank's
    *                 pages provides extra information
    *
    * @see #readPage(int,boolean,byte[],int,byte[]) readPage(extra)
    * @see #readPageCRC(int,boolean,byte[],int,byte[]) readPageCRC(extra)
    * @see #readPagePacket(int,boolean,byte[],int,byte[]) readPagePacket(extra)
    * @since 1-Wire API 0.01
    */
   public boolean hasExtraInfo ()
   {
      return extraInfo;
   }

   /**
    * Query to get the length in bytes of extra information that
    * is read when read a page in the current memory bank.  See
    * 'hasExtraInfo()'.
    *
    * @return  number of bytes in Extra Information read when reading
    *          pages in the current memory bank.
    */
   public int getExtraInfoLength ()
   {
      return extraInfoLength;
   }

   /**
    * Query to get a string description of what is contained in
    * the Extra Informationed return when reading pages in the current
    * memory bank.  See 'hasExtraInfo()'.
    *
    * @return string describing extra information.
    */
   public String getExtraInfoDescription ()
   {
      return extraInfoDescription;
   }

   /**
    * Set the write verification for the 'write()' method.
    *
    * @param  doReadVerf   true (default) verify write in 'write'
    *                      false, don't verify write (used on
    *                      Write-Once bit manipulation)
    */
   public void setWriteVerification (boolean doReadVerf)
   {
      writeVerification = doReadVerf;
   }

   //--------
   //-------- I/O methods
   //--------

   /**
    * Read  memory in the current bank with no CRC checking (device or
    * data). The resulting data from this API may or may not be what is on
    * the 1-Wire device.  It is recommends that the data contain some kind
    * of checking (CRC) like in the readPagePacket() method or have
    * the 1-Wire device provide the CRC as in readPageCRC().  readPageCRC()
    * however is not supported on all memory types, see 'hasPageAutoCRC()'.
    * If neither is an option then this method could be called more
    * then once to at least verify that the same thing is read consistantly.
    *
    * @param  startAddr     starting address
    * @param  readContinue  if 'true' then device read is continued without
    *                       re-selecting.  This can only be used if the new
    *                       read() continious where the last one led off
    *                       and it is inside a 'beginExclusive/endExclusive'
    *                       block.
    * @param  readBuf       byte array to place read data into
    * @param  offset        offset into readBuf to place data
    * @param  len           length in bytes to read
    *
    * @throws OneWireIOException
    * @throws OneWireException
    */
   public void read (int startAddr, boolean readContinue, byte[] readBuf,
                     int offset, int len)
      throws OneWireIOException, OneWireException
   {

      // check if read exceeds memory
      if ((startAddr + len) > size)
         throw new OneWireException("Read exceeds memory bank end");

      // attempt to put device at speed
      checkSpeed();

      // read the scratchpad, discard extra information
      readScratchpad(readBuf, offset, len, null);
   }

   /**
    * Write  memory in the current bank.  It is recommended that
    * when writing  data that some structure in the data is created
    * to provide error free reading back with read().  Or the
    * method 'writePagePacket()' could be used which automatically
    * wraps the data in a length and CRC.
    *
    * When using on Write-Once devices care must be taken to write into
    * into empty space.  If write() is used to write over an unlocked
    * page on a Write-Once device it will fail.  If write verification
    * is turned off with the method 'setWriteVerification(false)' then
    * the result will be an 'AND' of the existing data and the new data.
    *
    * @param  startAddr     starting address
    * @param  writeBuf      byte array containing data to write
    * @param  offset        offset into writeBuf to get data
    * @param  len           length in bytes to write
    *
    * @throws OneWireIOException
    * @throws OneWireException
    */
   public void write (int startAddr, byte[] writeBuf, int offset, int len)
      throws OneWireIOException, OneWireException
   {

      // return if nothing to do
      if (len == 0)
         return;

      // attempt to put device at speed
      checkSpeed();

      // check if write exceeds memory
      if ((startAddr + len) > size)
         throw new OneWireException("Write exceeds memory bank end");

      // write the page of data to scratchpad
      writeScratchpad(startPhysicalAddress + startAddr, writeBuf, offset,
                      len);

      // read to verify ok
      byte[] raw_buf   = new byte [pageLength];
      byte[] extra_buf = new byte [extraInfoLength];

      readScratchpad(raw_buf, 0, pageLength, extra_buf);

      // check to see if the same
      for (int i = 0; i < len; i++)
         if (raw_buf [i] != writeBuf [i + offset])
         {
            forceVerify();

            throw new OneWireIOException(
               "Read back verify had incorrect data");
         }

      // check to make sure that the address is correct
      if ((((extra_buf [0] & 0x00FF) | ((extra_buf [1] << 8) & 0x00FF00))
              & 0x00FFFF) != (startPhysicalAddress + startAddr))
      {
         forceVerify();

         throw new OneWireIOException("Read back address had incorrect data");
      }
   }

   //--------
   //-------- PagedMemoryBank I/O methods
   //--------

   /**
    * Read  page in the current bank with no
    * CRC checking (device or data). The resulting data from this API
    * may or may not be what is on the 1-Wire device.  It is recommends
    * that the data contain some kind of checking (CRC) like in the
    * readPagePacket() method or have the 1-Wire device provide the
    * CRC as in readPageCRC().  readPageCRC() however is not
    * supported on all memory types, see 'hasPageAutoCRC()'.
    * If neither is an option then this method could be called more
    * then once to at least verify that the same thing is read consistantly.
    *
    * @param  page          page number to read packet from
    * @param  readContinue  if 'true' then device read is continued without
    *                       re-selecting.  This can only be used if the new
    *                       readPage() continious where the last one
    *                       led off and it is inside a
    *                       'beginExclusive/endExclusive' block.
    * @param  readBuf       byte array to place read data into
    * @param  offset        offset into readBuf to place data
    *
    * @throws OneWireIOException
    * @throws OneWireException
    */
   public void readPage (int page, boolean readContinue, byte[] readBuf,
                         int offset)
      throws OneWireIOException, OneWireException
   {

      // check if read exceeds memory
      if (page != 0)
         throw new OneWireException("Page read exceeds memory bank end");

      // attempt to put device at speed
      checkSpeed();

      // read the scratchpad, discard extra information
      readScratchpad(readBuf, offset, pageLength, null);
   }

   /**
    * Read  page with extra information in the current bank with no
    * CRC checking (device or data). The resulting data from this API
    * may or may not be what is on the 1-Wire device.  It is recommends
    * that the data contain some kind of checking (CRC) like in the
    * readPagePacket() method or have the 1-Wire device provide the
    * CRC as in readPageCRC().  readPageCRC() however is not
    * supported on all memory types, see 'hasPageAutoCRC()'.
    * If neither is an option then this method could be called more
    * then once to at least verify that the same thing is read consistantly.
    * See the method 'hasExtraInfo()' for a description of the optional
    * extra information some devices have.
    *
    * @param  page          page number to read packet from
    * @param  readContinue  if 'true' then device read is continued without
    *                       re-selecting.  This can only be used if the new
    *                       readPage() continious where the last one
    *                       led off and it is inside a
    *                       'beginExclusive/endExclusive' block.
    * @param  readBuf       byte array to place read data into
    * @param  offset        offset into readBuf to place data
    * @param  extraInfo     byte array to put extra info read into
    *
    * @throws OneWireIOException
    * @throws OneWireException
    */
   public void readPage (int page, boolean readContinue, byte[] readBuf,
                         int offset, byte[] extraInfo)
      throws OneWireIOException, OneWireException
   {

      // check if read exceeds memory
      if (page != 0)
         throw new OneWireException("Page read exceeds memory bank end");

      // attempt to put device at speed
      checkSpeed();

      // read the scratchpad, discard extra information
      readScratchpad(readBuf, offset, pageLength, extraInfo);
   }

   /**
    * Read a Universal Data Packet.
    *
    * The Universal Data Packet always starts on page boundaries but
    * can end anywhere in the page.  The structure specifies the length of
    * data bytes not including the length byte and the CRC16 bytes.
    * There is one length byte. The CRC16 is first initialized to
    * the page number.  This provides a check to verify the page that
    * was intended is being read.  The CRC16 is then calculated over
    * the length and data bytes.  The CRC16 is then inverted and stored
    * low byte first followed by the high byte.  This is structure is
    * used by this method to verify the data but is not returned, only
    * the data payload is returned.
    *
    * @param  page          page number to read packet from
    * @param  readContinue  if 'true' then device read is continued without
    *                       re-selecting.  This can only be used if the new
    *                       readPagePacket() continious where the last one
    *                       stopped and it is inside a
    *                       'beginExclusive/endExclusive' block.
    * @param  readBuf       byte array to put data read. Must have at least
    *                       'getMaxPacketDataLength()' elements.
    * @param  offset        offset into readBuf to place data
    *
    * @return  number of data bytes read from the device and written to
    *          readBuf at the offset.
    *
    * @throws OneWireIOException
    * @throws OneWireException
    */
   public int readPagePacket (int page, boolean readContinue, byte[] readBuf,
                              int offset)
      throws OneWireIOException, OneWireException
   {
      byte[] raw_buf = new byte [pageLength];

      // attempt to put device at speed
      checkSpeed();

      // read the scratchpad, discard extra information
      readScratchpad(raw_buf, 0, pageLength, null);

      // check if length is realistic
      if (raw_buf [0] > maxPacketDataLength)
      {
         forceVerify();

         throw new OneWireIOException("Invalid length in packet");
      }

      // verify the CRC is correct
      if (CRC16.compute(raw_buf, 0, raw_buf [0] + 3, page) == 0x0000B001)
      {

         // extract the data out of the packet
         System.arraycopy(raw_buf, 1, readBuf, offset, raw_buf [0]);

         // return the length
         return raw_buf [0];
      }
      else
      {
         forceVerify();

         throw new OneWireIOException("Invalid CRC16 in packet read");
      }
   }

   /**
    * Read a Universal Data Packet and extra information.  See the
    * method 'readPagePacket()' for a description of the packet structure.
    * See the method 'hasExtraInfo()' for a description of the optional
    * extra information some devices have.
    *
    * @param  page          page number to read packet from
    * @param  readContinue  if 'true' then device read is continued without
    *                       re-selecting.  This can only be used if the new
    *                       readPagePacket() continious where the last one
    *                       stopped and it is inside a
    *                       'beginExclusive/endExclusive' block.
    * @param  readBuf       byte array to put data read. Must have at least
    *                       'getMaxPacketDataLength()' elements.
    * @param  offset        offset into readBuf to place data
    * @param  extraInfo     byte array to put extra info read into
    *
    * @return  number of data bytes read from the device and written to
    *          readBuf at the offset.
    *
    * @throws OneWireIOException
    * @throws OneWireException
    */
   public int readPagePacket (int page, boolean readContinue, byte[] readBuf,
                              int offset, byte[] extraInfo)
      throws OneWireIOException, OneWireException
   {
      byte[] raw_buf = new byte [pageLength];

      // attempt to put device at speed
      checkSpeed();

      // read the scratchpad, discard extra information
      readScratchpad(raw_buf, 0, pageLength, extraInfo);

      // check if length is realistic
      if (raw_buf [0] > maxPacketDataLength)
      {
         forceVerify();

         throw new OneWireIOException("Invalid length in packet");
      }

      // verify the CRC is correct
      if (CRC16.compute(raw_buf, 0, raw_buf [0] + 3, page) == 0x0000B001)
      {

         // extract the data out of the packet
         System.arraycopy(raw_buf, 1, readBuf, offset, raw_buf [0]);

         // return the length
         return raw_buf [0];
      }
      else
      {
         forceVerify();

         throw new OneWireIOException("Invalid CRC16 in packet read");
      }
   }

   /**
    * Write a Universal Data Packet.  See the method 'readPagePacket()'
    * for a description of the packet structure.
    *
    * @param  page          page number to write packet to
    * @param  writeBuf      data byte array to write
    * @param  offset        offset into writeBuf where data to write is
    * @param  len           number of bytes to write
    *
    * @throws OneWireIOException
    * @throws OneWireException
    */
   public void writePagePacket (int page, byte[] writeBuf, int offset,
                                int len)
      throws OneWireIOException, OneWireException
   {

      // make sure length does not exceed max
      if (len > maxPacketDataLength)
         throw new OneWireException(
            "Length of packet requested exceeds page size");

      // see if this bank is general read/write
      if (!generalPurposeMemory)
         throw new OneWireException(
            "Current bank is not general purpose memory");

      // construct the packet to write
      byte[] raw_buf = new byte [len + 3];

      raw_buf [0] = ( byte ) len;

      System.arraycopy(writeBuf, offset, raw_buf, 1, len);

      int crc = CRC16.compute(raw_buf, 0, len + 1, page);

      raw_buf [len + 1] = ( byte ) (~crc & 0xFF);
      raw_buf [len + 2] = ( byte ) (((~crc & 0xFFFF) >>> 8) & 0xFF);

      // write the packet, return result
      write(page * pageLength, raw_buf, 0, len + 3);
   }

   /**
    * Read a complete memory page with CRC verification provided by the
    * device.  Not supported by all devices.  See the method
    * 'hasPageAutoCRC()'.
    *
    * @param  page          page number to read
    * @param  readContinue  if 'true' then device read is continued without
    *                       re-selecting.  This can only be used if the new
    *                       readPagePacket() continious where the last one
    *                       stopped and it is inside a
    *                       'beginExclusive/endExclusive' block.
    * @param  readBuf       byte array to put data read. Must have at least
    *                       'getMaxPacketDataLength()' elements.
    * @param  offset        offset into readBuf to place data
    *
    * @throws OneWireIOException
    * @throws OneWireException
    */
   public void readPageCRC (int page, boolean readContinue, byte[] readBuf,
                            int offset)
      throws OneWireIOException, OneWireException
   {

      // only needs to be implemented if supported by hardware
      throw new OneWireException(
         "Read page with CRC not supported by this memory bank");
   }

   /**
    * Read a complete memory page with CRC verification provided by the
    * device with extra information.  Not supported by all devices.
    * See the method 'hasPageAutoCRC()'.
    * See the method 'hasExtraInfo()' for a description of the optional
    * extra information.
    *
    * @param  page          page number to read
    * @param  readContinue  if 'true' then device read is continued without
    *                       re-selecting.  This can only be used if the new
    *                       readPagePacket() continious where the last one
    *                       stopped and it is inside a
    *                       'beginExclusive/endExclusive' block.
    * @param  readBuf       byte array to put data read. Must have at least
    *                       'getMaxPacketDataLength()' elements.
    * @param  offset        offset into readBuf to place data
    * @param  extraInfo     byte array to put extra info read into
    *
    * @throws OneWireIOException
    * @throws OneWireException
    */
   public void readPageCRC (int page, boolean readContinue, byte[] readBuf,
                            int offset, byte[] extraInfo)
      throws OneWireIOException, OneWireException
   {

      // only needs to be implemented if supported by hardware
      throw new OneWireException(
         "Read page with CRC and extra-info not supported by this memory bank");
   }

   //--------
   //-------- ScratchPad methods
   //--------

   /**
    * Read the scratchpad page of memory from a NVRAM device
    * This method reads and returns the entire scratchpad after the byte
    * offset regardless of the actual ending offset
    *
    * @param  readBuf       byte array to place read data into
    *                       length of array is always pageLength.
    * @param  offset        offset into readBuf to pug data
    * @param  len           length in bytes to read
    * @param  extraInfo     byte array to put extra info read into
    *                       (TA1, TA2, e/s byte)
    *                       length of array is always extraInfoLength.
    *                       Can be 'null' if extra info is not needed.
    *
    * @throws OneWireIOException
    * @throws OneWireException
    */
   public void readScratchpad (byte[] readBuf, int offset, int len,
                               byte[] extraInfo)
      throws OneWireIOException, OneWireException
   {
      // select the device
      if (!ib.adapter.select(ib.address))
      {
         forceVerify();

         throw new OneWireIOException("Device select failed");
      }

      // build first block
      byte[] raw_buf = new byte [1 + extraInfoLength];

      raw_buf [0] = READ_SCRATCHPAD_COMMAND;

      System.arraycopy(ffBlock, 0, raw_buf, 1, extraInfoLength);

      // do the first block for TA1, TA2, and E/S
      ib.adapter.dataBlock(raw_buf, 0, 1 + extraInfoLength);

      // optionally extract the extra info
      if (extraInfo != null)
         System.arraycopy(raw_buf, 1, extraInfo, 0, extraInfoLength);

      // build the next block
      System.arraycopy(ffBlock, 0, readBuf, offset, len);

      // send second block to read data, return result
      ib.adapter.dataBlock(readBuf, offset, len);
   }

   /**
    * Write to the scratchpad page of memory a NVRAM device.
    *
    * @param  startAddr     starting address
    * @param  writeBuf      byte array containing data to write
    * @param  offset        offset into readBuf to place data
    * @param  len           length in bytes to write
    *
    * @throws OneWireIOException
    * @throws OneWireException
    */
   public void writeScratchpad (int startAddr, byte[] writeBuf, int offset,
                                int len)
      throws OneWireIOException, OneWireException
   {

      // select the device
      if (!ib.adapter.select(ib.address))
      {
         forceVerify();

         throw new OneWireIOException("Device select failed");
      }

      // build block to send
      byte[] raw_buf = new byte [3 + len];

      raw_buf [0] = WRITE_SCRATCHPAD_COMMAND;
      raw_buf [1] = ( byte ) (startAddr & 0xFF);
      raw_buf [2] = ( byte ) (((startAddr & 0xFFFF) >>> 8) & 0xFF);

      System.arraycopy(writeBuf, offset, raw_buf, 3, len);

      // send block, return result
      ib.adapter.dataBlock(raw_buf, 0, len + 3);
   }

   /**
    * Copy the scratchpad page to memory.
    *
    * @param  startAddr     starting address
    * @param  len           length in bytes that was written already
    *
    * @throws OneWireIOException
    * @throws OneWireException
    */
   public void copyScratchpad (int startAddr, int len)
      throws OneWireIOException, OneWireException
   {

      // select the device
      if (!ib.adapter.select(ib.address))
      {
         forceVerify();

         throw new OneWireIOException("Device select failed");
      }

      // build block to send
      byte[] raw_buf = new byte [5];

      raw_buf [0] = COPY_SCRATCHPAD_COMMAND;
      raw_buf [1] = ( byte ) (startAddr & 0xFF);
      raw_buf [2] = ( byte ) (((startAddr & 0xFFFF) >>> 8) & 0xFF);
      raw_buf [3] = ( byte ) ((startAddr + len - 1) & 0x1F);
      raw_buf [4] = ( byte ) 0xFF;

      // send block (check copy indication complete)
      ib.adapter.dataBlock(raw_buf, 0, 5);

      if ((raw_buf [4] & 0x0F0) != 0)
      {
         forceVerify();

         throw new OneWireIOException("Copy scratchpad complete not found");
      }
   }

   //--------
   //-------- checkSpeed methods
   //--------

   /**
    * Check the device speed if has not been done before or if
    * an error was detected.
    *
    * @throws OneWireIOException
    * @throws OneWireException
    */
   public void checkSpeed ()
      throws OneWireIOException, OneWireException
   {
      synchronized (this)
      {
         // only check the speed
         // 9-23-2003 shughes: added the check to see if the adapter is
         // currently at the ibutton's max speed.  If it isn't, we should
         // call the doSpeed() method, since the adapter might have
         // changed speeds.
         if (doSetSpeed || (ib.adapter.getSpeed()!=ib.getMaxSpeed()))
         {
            // attempt to set the correct speed and verify device present
            ib.doSpeed();

            // no execptions so clear flag
            doSetSpeed = false;
         }
      }
   }

   /**
    * Set the flag to indicate the next 'checkSpeed()' will force
    * a speed set and verify 'doSpeed()'.
    */
   public void forceVerify ()
   {
      synchronized (this)
      {
         doSetSpeed = true;
      }
   }
}
